In related art, the size of pixels of solid-state image sensors typified by CMOS image sensors tends to be reduced for the purpose of increasing the number of pixels or the like, and in this case, there are problems of decrease in sensitivity and decrease in S/N due to reduction in the number of photons incident on the pixels.
In addition, in many solid-state image sensors, the top surface of each pixel is covered with a color filter of R, G, or B, and, for example, in a pixel covered with an R color filter (hereinafter referred to as an R pixel; this also applies to a G pixel and a B pixel), only the R component of incident light is used for photoelectric conversion while the G and B components of incident light are not used for photoelectric conversion, which causes a loss in sensitivity correspondingly. Furthermore, since an R pixel can generate an R-component signal but cannot generate a G-component signal and a B-component for example, the G-component and B-component signals are interpolated with use of outputs from a G pixel or a B pixel in the vicinity, which can cause false colors.
Thus, as a measure to solve these problems, a solid-state image sensor having three photoelectric conversion layers, which correspond to the respective wavelengths of R, G, and B in one pixel, stacked vertically, and being thus capable of generating an R-component signal, a G-component signal, and a B-component signal in one pixel is proposed (refer, for example, to Patent Document 1).